Hey! We haven’t implemented post searching yet, though we’ll be implementing it in the next version of Mlem (2.0).
To block an instance, you need to go to the instance page. You can do this by searching for the instance in the “Search” tab, or by tapping the (…)
button in the top-right of a community page or profile page and tapping the instance name. In the instance page, you can tap the (…)
button in the top-right and then choose “block” to block the instance.
To view blocked instances go to the Settings tab, then tap the button at the top of the page (your username), then tap “Blocklist”.
Mlem dev here. You can attach a link to the post directly by clicking the link button in the post editor toolbar then tapping "Paste" (with a link copied to clipboard). We're aware that this isn't the most obvious UI, and are improving the design in the next version.